The invention relates to a Jacquard heald for use in Jacquard machines.
In accordance with document GB 807945 Jacquard healds are manufactured, for example, in that two adjacent wires are initially soldered together. The soldered-together wires are then separated again in one region and are slightly bent apart. Then a thread eye insert (maillon) is soldered into the thusly formed opening, said insert forming the thread eye.
A similar procedure has been known from document EP 1 015 675 B1. Again, initially, two wires are used that are firmly connected to each other by being tin-plated or nickel-plated. In one region, the wires are detached from each other and bent away from each other in order to insert a thread eye insert. An adhesive is then used to secure the latter in place between the wires.
It is true that, due to this measure, it is no longer necessary to solder the thread eye inserts in place, however, the previous manufacture of the twin wire is still required.
In order to avoid this disadvantage, it has been suggested, for example in EP 1 252 944, to use a profiled wire instead of the twin wire as the starting material, said profiled wire have an approximately octagonal cross-section. However, such profiled wires are generally not commercially available.
The considerably older document U.S. Pat. No. 569,149 A discloses the manufacture of healds from round wire, in which case, a central region is converted into a flat shape by plastic reformation in order to produce the thread eye. Then, the thread eye is punched into this region. This procedure results in a significant weakening of the tensile strength of the heald at the thread eye.
This is remedied by document DE 121 105 which uses a relatively thick wire for the manufacture of the heald. While a central region of the wire remains initially without deformation, the two axially adjoining sections are elongated in axial direction so that their diameter decreases. The remaining thick central section is then flattened to a thickness that corresponds to the diameter of the elongated regions. Then, again, an oval opening is punched into the resultant oval flattened region, whereby a thread eye insert can be placed in said opening.
This process is tedious. The elongation of the wire is little suitable for mass production.
Another approach can be learned from document EP 0 947 620. There, the suggestion has been made to start with a ribbon in which a narrow opening is applied and then widened in order to apply a thread eye insert. Inasmuch as the thread eye inserts have a thickness starting at approximately 0.35 mm, such a heald has a relatively large ribbon cross-section. Consequently, the heald becomes relatively heavy, this being undesirable in view of the fact that the heald movements are controlled by springs.
Document EP 1 767 676 represents a supplement to the aforementioned publication, as it were, disclosing the improvement of the fastening options for the thread eye insert.
Document DE 195 09 03 suggests the use of a round wire as the starting material instead of a flat ribbon, said wire being rolled flat during a first manufacturing step. As a result of this, rounded lateral edges are formed next to the two flat sides formed by the rollers. Longitudinally extending notches are then embossed in the flat sides of the flattened wire, at which notches the heald can be easily split in order to apply a thread eye insert.
A completely different direction is taken by document JPS 57-117646. The heald shown there starts with a round wire to which a flattened region is applied. An opening is embossed in said region, said opening being delimited by two remaining flat legs. The opening is narrower than a thread eye that is to be inserted. In order to achieve the necessary width, the remaining legs are twisted in longitudinal direction so that their cross-section is diagonal to the thread eye. The resultant asymmetrical form is particularly disadvantageous during the weaving operation, in particular considering the thread that is sliding past the heald.
It is the object of the present invention to provide a Jacquard heald that can be manufactured in a cost-effective manner without compromising the quality. The above-described disadvantages are to be avoided as much as possible.